 Re: there are/were two persons understanding Confucius.
Here you could rephrase it as : There have only ever been two people with a good understanding of Confucius' philosophy : XXX, who lived in the Xth century and XXXX, who teaches at the university of XXX. Or whatever the details are. It's the same problem as before - the lack of a single verb for both people. So I've replaced ..who understood/understand with the noun phrase : with a good understanding of |